Here’s the essence of 2005’s “Freakonomics,” which sold four million copies, and its equally delightful follow-up: this stuff is Dan Brown for smart people. Secret webs of knowledge hidden in plain sight, reviled underdogs digging up the truth, distrust of institutions: It’s all here, and it’s magnificent stuff. Short, simple and written in prose an eighth-grader could understand, this book is nevertheless a brain buffet.As in their earlier blockbuster, the University of Chicago economist (Levitt) and the writer (Dubner) roam through human nature teaching how to think like an economist — that incentives matter.

The first book made startling, indeed incendiary, claims (the authors attributed the nationwide fall in crime in the 1990s to Roe V. Wade, pointing out that many Americans born to be jailed are no longer being born at all).

“Superfreakonomics”? It merely solves hurricanes and global warming, gives advice to terrorists and proves that monkeys can be hookers.

“You may find a few things in the following pages to quarrel with,” the authors promise at the beginning.

And how! A few pages later they’re saying that if your only options are walking home drunk and driving home drunk, you should pick the latter. (Since drunk walkers are eight times more likely to be killed than drunk drivers).

The most intriguing chapters are inspired by Microsoft alum Nathan Myhrvold (“I don’t know anyone I would say is smarter than Nathan,” Bill Gates once said).

Myhrvold’s hurricane killer is a seawall of giant funky man-made jellyfish in the Caribbean — 600-foot floating cylinders that would churn hot hurricane-causing surface water beneath the cold water underneath. The cost would be a fraction of the property damage done by hurricanes in a single rough season.

Even better: Myrhvold says he could reverse global warming simply by installing a giant garden hose at the North Pole and injecting a spritz of sulfur dioxide into the stratosphere — imitating the effects of the 1991 eruption of Mount Pinatubo, which swathed the planet with a nice protective sunscreen. The cost, at $250 million, would be so low that one foundation — even a wealthy individual — could bankroll it. Al Gore and his acolytes would rather spend trillions of other people’s money redesigning the economy.

And Gore, naturally, is on record as saying geoengineering is “nuts.” Why wouldn’t he? He has colossal interests at stake — not only his outsized reputation but his evidently wasted lifetime of doomsaying.

The book broadly mocks Gore-ism, pointing out the dangers of unintended consequences (the Americans with Disabilities Act scared employers away from hiring the disabled), emphasizing simple solutions instead of government fiats (doctors’ hand-washing in Cedars-Sinai hospital skyrocketed when a screen-saver displayed their bacteria-laden handprints) and noting that altruism (such as in the market for kidney transplants) isn’t much of an incentive.

“Freakonomics” is brave, bracing and beautifully contrarian. Don’t go to the water cooler without it.